Procedure and means for changing a press fabric in the press section of a paper machine

ABSTRACT

Method for changing a felt (20) in the press section of a paper machine. The normal run of said felt (20) passes in a substantial part in spaces (K) under the floor level (T--T) of the paper machine hall. In said press section its lower roll (12) is rotatably carried in support by one or several cantilevered beams (30). In the procedure the frame inserts (38) carrying one end of said cantilevered beam (30) are first removed and then lifting means (33,33&#39;) provided in conjunction with said cantilevered beam (30) is used to lift the guide roll or guide rolls (15,17) coming to lie within the loop of the felt to be changed and located in the underside space (K), into an upper position (15,15&#39;) to be adjacent to the cantilevered beam (30). After that the loop (50) of the new felt is spread out to the configuration implied by the rolls coming to lie therewithin, in which shape the felt loop (50) is pushed, using special equipment (40,41,42,43,44,45,46,47 ), to encircle the rolls (12,13,14,15 and 17) coming to lie inside the loop and around said cantilevered beam (30) through the space vacated by said removed inserts (38). Then the rolls (15&#39;,17&#39;) lifted into the upper position are lowered with their lifting means (33,33&#39;) into their operating position in the underside space (K), whereupon said frame inserts (38) are closed.

BACKGROUND OF THE INVENTION

The present invention concerns, in the press section of a paper machine,in particular in a so-called closed-conduction press section, aprocedure for changing such a felt of which the normal run passes to asubstantial part in spaces below floor level, said press section havingits lower roll and the potential guide rolls of the felt to be changedwhich are located adjacent thereto, rotatably carried by one or severalcantilever beams.

Furthermore, the invention concerns a means intended for implementingthe procedure of the invention and which is applied in connection withthe press section, preferably a so-called closed conduction presssection, of a paper machine, and said press section comprising acantilevered beam, in connection of which have been rotatably carriedthe lower roll of the press and potential felt guide rolls in itsvicinity, and one end of said cantilevered beam being supported by oneor several inserts which can be taken out for the lower changingoperation.

Recently, press fabrics made of synthetic plastic materials have comeinto common use in paper machine press sections, replacing the textilefabrics which were commonly used before. However, the introduction ofthese new fabric types has introduced problems associated with thechanging of these fabrics. As known in the art, of course, textilefabrics were changed, e.g., so that the felt loop is stuffed inhorizontal direction to become a kind of bundle and, starting to spreadthis out from one edge the felt loop is carried in through the gaps atthe removed inserts, to be looped around those rolls which the felt loopwill in its operation encircle and lap.

In so-called closed press sections, for instance the same applicant'sSym-Press II (Trademark) press section, the changing of syntheticfabrics involves immense problems. With a view to illustrating theseproblems, the structural design of said Sym-Press II press section shallnow be described in its main features. It is well known that theSym-Press II press section comprises at least three felts (pressfabrics, in general): a first felt, e.g. a pick-up felt operating aspress felt in the first and second nips of the press section, and asecond felt operating as second press felt in the first nip, and thispress section comprises a suction roll passed over by the first pressfelt, e.g. a pick-up felt. In conjunction with this suction roll twopress nips are formed, of which the first press nip is two-felted, beingdefined by this roll together with a recessed surface press roll, andthe second presents a single felt and is defined by said roll togetherwith a smooth-surfaced roll, e.g. a stone roll. In conjunction of saidstone roll or equivalent has further been provided the third press nipof the press section, which has its third felt (fabric loop). Changingof the upper felts in the Sym-Press press section and of otherequivalent closed conduction upper felts, that is of those felts whoserun is mainly located above the base floor level of the paper machine,is mainly possible to carry out with the aid of the overhead hoists orcranes in the paper machine hall. By the changing of the lower pressfelt in the Sym-Press press section has become a particularly refractoryproblem, i.e., that of the lower felt of the first two-felted nip. Thisis because said lower felt runs through the basement space of the papermachine hall, where it is not possible, at least not without expensivespecial arrangements, to use the overhead cranes of the paper machinehall.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide aprocedure, or means, applicable in connection with the Sym-Press presssection or other equivalent press sections and whereby the fabrics, orfabric, of these press sections running a substantial part of its run inthe basement space of the paper machine hall can be changed ratherrapidly and using comparatively simple apparatus.

It is a special object of the invention: to provide a procedure and ameans by which the fabrics mentioned may also be changed when they aresuch synthetic plastic fabrics which cannot be crammed to small bulk, orotherwise folded, in the transversal direction of the fabric loop.

In the prior art is known a procedure for changing a running felt, orfelts, wherein the rolls in basement space which come to lie within thefelt loop are raised with the aid of wires to be vertical and the newfelt loop is introduced over these rolls in vertical position. However,this procedure of prior art is not applicable, at least not withoutdifficulty, in the changing of those synthetic fabrics which must not befolded.

With a view to achieving the objects stated above, and others which willbecome apparent later on, the procedure of the invention is mainlycharacterized in that:

the insert in the frame support one end of said cantilevered beam isremoved;

a lifting means provided in conjunction with said cantilevered beam, ora plurality of such means, is used to lift the guide roll, or guiderolls, intended to be within the felt that is being changed, in thedown-below space, into an upper position adjacent to the cantileveredbeam;

the loop of the new felt is spread to a configuration conforming to therolls which will be located within this loop, special appliances beingused to push the felt loop around the rolls to be placed within the loopand the said cantilevered beam through the free gap provided by said,removed inserts; and

the roll/rolls lifted into upper position is/are lowered with thelifting means into the lower space, whereupon the said frame inserts aremounted to close the gaps.

The means of the invention is mainly characterized in that:

adjacent to said cantilevered beam, or inside it, has been provided oneor several lifting means comprising wire reels which have been connectedto drive means, and

on said wire reels have been provided lifting wires for lifting theunderside guide rolls operating within the felt loop, into an upperposition in connection with said cantilevered beam.

The invention teaches to dispose the lifting means for the guide rollsof the fabrics of the press section which are located in basement space,in conjunction with the cantilevered frame beam of the press section.Hereby this even otherwise comparatively robust frame beam, or thesebeams, can be utilized to advantage, because it should be noted that inpaper machines with great breadth the press fabrics' guide rolls have acomparatively great weight (their weight being e.g. 2000 to 3000 kg).

When performing change of press fabrics by the procedure of theinvention, one may in certain steps also make use of the overhead cranein the paper machine hall. However, this crane may only be used tosupport the bracing tube of the fabric package that is being changed, inthe space outside the frame interval of the paper machine, and in whichconnection no similar problems occur as are encountered if the overheadcranes of the paper machine hall were used for the lifting of the saidheavy fabric guiding rolls in the basement space.

According to a favourable embodiment of the invention, the same means bywhich the guide rolls having their place within the lower felt loop arelifted into their upper position for felt changing, are also employedtowards changing guide rolls in the basement space, to wit, even rollswhich have their place outside the lower felt loop, and possibly otherrolls. In such case, furthermore, that carriage means by which the tubebracing the felt loop that is being changed is displaced longitudinally,may also be used towards moving the guide rolls which are being changed.It is thus understood that by the lifting means of the invention theguide rolls to be changed may be lifted out from the basement space andtransported, using the said carriage, to one side of the paper machineand the new roll can by using the same means be moved, first from theside of the paper machine into the paper machine and, thereafter, it maybe lowered, using said means, into the basement space to its properoperating place.

BRIEF DESCRIPTION OF THE DRAWING

In the following, the invention is described in detail with referencebeing made to an embodiment example of the invention presented in thefigures of the attached drawing, to the details of which the inventionis not confined.

FIG. 1 presents in elevational view, the means applying the procedure ofthe invention, in connection with the ∓Sym-Press II" press section of apaper machine.

FIG. 2 shows the section II--II from FIG. 1.

FIG. 3 illustrates the felt loop running-in phase, wherein a crane isused as aid.

FIG. 4 presents schematically the use of the means of the invention inthe changing of various guide rolls in the basement.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2 show the so-called "Sym-Press II" (Trademark) presssection only its underside members. This press comprises the suctionroll 10, in connection of which the press nips N₁ and N₂ become defined.The first press nip N₁ is two-felted, being defined between the pick-upfelt 27 and the lower felt 20. The lower felt runs under guidance by theguide rolls 13,14,15,16,17 and 18. The first felt 27 also operates aspress felt in the second nip N₂. The lower roll 12 of the first nip N₁is a recessed surface roll, e.g. a grooved roll. The third roll of thepress section 11, is a smooth-surfaced roll, for instance a stone roll,and in its conjunction is defined the third nip (not depicted) of thepress section, which has also been provided with a felt of its own (notdepicted).

In the foregoing, in association with the fabrics 20 and 27, the talkhas been of "felts", and it has now to be understood that "felt" hasbeen used as general application covering all and any kinds of fabricand, in particular, also synthetic plastic fabrics, which--as observedbefore--cannot be folded or otherwise "wrinkled".

The present invention comprises a procedure and a means by which in apress section as described, or in other equivalent press sections, thelower felt 20, to wit, a felt running in basement or equivalent spaces,can be changed. As FIG. 1 reveals, the lower felt 20 runs in thebasement space K under the floor level T--T of the paper machine hall,where it is not possible without difficulties to operate with theoverhead cranes of the paper machine hall. The felt 20, which is forinstance a felt of synthetic plastic, runs after the press nip N₁ ontothe guide roll 14 and thence downward to the guide roll 15. After theguide roll 15, the felt 20 has been conducted to the roll 16, which isexternal to the felt loop. On the felt run 20 between rolls 15 and 16,felt reconditioning means 25 known in themselves in the art have beenprovided. From the roll 16, the felt 20 has been conducted to the guideroll 17, which has been mounted on the slide 24. It is possible bydisplacing the slide 24 on its guides 23, to carry out the basic tensionadjustment of the felt loop 20. Reference numeral 17a indicate thelowermost extreme position of the guide roll 17. Following after theroll 17 on the path of the felt 20 has been provided a guide roll 18,which can be used in a manner known in itself in the art, with the aidof bellows means 26 or equivalent, towards fine adjustment of thetension of felt 20. After the roll 18, the run of the felt loop 20 isupwardly directed all the way up to the guide roll 13.

The following is a description, with particular reference to FIG. 2, ofthe frame structure of the press section in such event as is necessaryfor the understanding of the present invention. The paper machine hallhas foundations 100 known in themselves in the art, between which alsois defined the basement space K, of which the breadth has been denotedwith L₁. The lower roll 12 of the press section, the guide rolls 13 and14 of the felt 20 and the lifting means 33 and 33' of the invention havebeen supported with the cantilevered beam 30. The beam 30 is carried onthe foundation 100 by mediation of the side frames 36a and 36b. On theoperator's side of the machine, to the beam 30 has been connected acantilever part 31, which has been affixed to the foundation by theanchor 32. In connection with the side frame 36b of the beam 30 havebeen provided two inserts 38, which may be taken out by means of apull-in carriage provided for the inserts 38--after the beam 30 and itsside frame 36b have been slightly raised by means of the hydrauliccylinder 37. If there is a plurality of beams 30 side by side, each suchbeam will have its own cantilever part 31 and an anchor 32 in connectiontherewith.

Within the beam 30 have been disposed the lifting means 33 and 33' forthe rolls 15 and 17 to be located in the basement space K within thefelt loop 20. These means consist of a shaft 39 rotatably carriedbetween the side frames 36a and 36b and carrying on both ends wire drums34a and 34b. On the drums 34a and 34b have been wound wire ropes 21 orequivalent pulling members. The shafts 33 are driven by hydraulic motors35 or equivalent. Moreover, for the change of the felt 20 there has beenprovided in the vicinity of one shaft 33 and thereinunder, a carriage 40for driving the felt package 50 in. The carriage 40 moves on its wheels41 along the track 42. In connection with the carriage 40, is mountedthe bracing tube 43 for the felt package 50; this tube has on its end ahandwheel 47 for the felt-spreading operation.

Although the talk was of one cantilevered beam 30 in the foregoing, theinvention may equally be applied in press section designs having two ormore separate cantilevered beams or other equivalent frame parts insteadof the beam 30. It should further be noted that although in theforegoing in association with one beam 30 two searate lifting means 33and 33' have been described; it should be understood that equally thoseproblem solutions are within the scope of the invention in which one,two or even more lifting means are employed, depending on how many rollslocated within the felt loop 20 need to be lifted into their upperposition in connection with a felt change. It should be noted in thisconnection that one and the same lifting means may be used to lift intothe upper position even more than one roll provided that the rolls havea small enough mutual horizontal distance. It is possible in that caseto provide in connection with the frame beam 30 or equivalent, specialsupporting members on which the roll, that has been lifted up, is leftto rest while another roll is being lifted into top position. In theembodiment depicted in the figures, the guide roll lifting members 21 atthe same time operate as members supporting the rolls in their topposition. As has been pointed out, this design is not the only liftingmeans design within the scope of the invention.

In the following is described the changing of the felt 20, making use ofthe means just described. The old felt 20 is removed by cutting open theloop which it forms. Next, the new felt 50 wound around the bracing tube43 is conveyed into the position shown in FIG. 3, where the bracing tube43 is supported by means of the wire 44, with a hook 45 attached to thecrane wire 46. The crane wire 46 has been attached e.g. to a craneoperating under the ceiling of the paper machine hall (not depicted).The new felt 50 may be wound around the bracing tube 43 in such mannerthat the tube 43 comes to lie within or outside the felt loop 50. Careshould be taken in this connection to see that the felt loop 50 is notfolded too sharply. In the case that the bracing tube 43 comes to liewithin the felt loop 50, the bracing tube must be moved to one side, andremoved from within the felt loop 50, after the felt 50 has been slippedin.

To the purpose of felt changing, the rolls 17 and 15 have to be liftedto be close to the rolls 12,13 and 14. This is done with the liftingmeans 33,33' described above. As shown in FIGS. 1 and 2, the roll 17 hasfirst been lifted on its slide 24 moving on the guides 23, into theupper position 17b and it has been separated from its bearing supports.In this position, the wires 21 are attached to the journal pins 22 ofthe roll 17 in position 17b. The roll 17 is thereafter lifted into theupper position 17', shown in FIGS. 1 and 2, between the frame structures36a and 36b. In similar manner, the lifting means 33' are used to liftthe roll 15 into its upper position 15'.

After the said measures have been carried out, the new felt 50 woundupon the bracing tube 43 is spread out--by operating the crank 47--sothat the felt loop assumes the position shown with dot-and-dash lines 50in FIG. 1. The location of the felt package 50 in the breadth direction(cross-machine direction) at this stage has been indicated withreference L₂ in FIG. 3. The felt 50 is held in this position either bymanpower or with special auxiliary means. The inserts 38 of the sideframe 36b have been removed, the cantilevered frame beam 30 being heldover its cantilever part 31 by the anchor 32 and, thus, by thefoundation 100. The lifting wire 46 is now used to exert a pull in thedirection of arrow F (FIG. 3), causing the carriage 40 to move on itswheels 41 on the track 42. At the same time the felt loop 50 is guidedin over the rolls 12,13 and 14 with the nip N₁ opened. In this way thefelt loop 50 can be transposed into its correct position around therolls 12,13,14,15,17 and the frame beam 30, whereafter the hand crank 47is operated to unwind more of the felt loop from its bracing tube 43. Atthe same time the rolls 15' and 17' may be lowered in their supports 21into the bearing supports on the slide 24 and into the respectivebearing supports of roll 15. The new felt 50 may then be tensioned inthe place of the felt 20. If it is not possible to support the bracingtube 43 from above with the crane wire 46, one may arrange for it asuitable support from below, and a work means and/or equivalent pullingmeans.

In the following shall be described, referring now to FIG. 4, the use ofthe means of the invention in the changing of guide rolls 15,16,17,18and other equivalent apparatus located in the basement, which operationhas previously presented problems. As shown in FIG. 4, the wires 21 ofthe lifting means 33 are attached to the journal pins of the roll to bechanged, 17b', and this roll is lifted into the upper position 17".Next, the carriage 40 which has been provided to be displaceable on thebeams 53, supported by the guides 52, under effect of the hydrauliccylinder 51, is moved into its position under the roll 17", indicatedwith dot-and-dash lines. The wires 21 may now be loosened so that theroll 17" settles to be carried by the carriage 40. The carriage 40 isthen with the hydraulic cylinders 41 pulled into the position in whichthe roll assumes the location indicated with 17"'. In this position theroll 17"' may be pulled to one side of the paper machine and a new rollmay be brought and installed, repeating the steps just described, ininverted order. It is likewise possible, in the manner described, tolift out from the basement space the rolls 15,16 and 18 and other rollsor pieces of apparatus to the lifting of which the lifting means 33,33'are particularly well suited.

In the following are presented the claims, different details of theinvention being allowed to vary within the scope of the inventive ideathereby defined.

I claim:
 1. Method for changing a felt which forms a part of a presssection of a paper machine, said press section including a felt having arun which passes above and below a certain level of said machine, over alower press roll above said certain level, and over at least one firstguide roll substantially adjacent to said lower press roll, said lowerpress roll and said at least one first guide roll being rotatablysupported by at least one cantilever beam, said cantilever beamsupported by at least one insert, wherein said insert is removed duringthe felt changing operation, the improvement comprising the stepsoflifting both ends of at least one second guide roll disposed belowsaid certain level, to an upper position substantially adjacent to saidat least one cantilever beam, maintaining said lower press rollsubstantially in position when said at least one second guide roll islifted, inserting a new felt around said lower press roll and aroundsaid first and second guide rolls through a space created by removingsaid at least one insert, lowering said at least one second guide rollto its original position, and re-introducing said at least one insert.2. The method of claim 1 in which the new felt is inserted by the stepsofdisposing said new felt in a wound configuration on elongated bracingmeans supported on one end by at least one hoisting wire and on theother end on said machine through carriage means adapted to slide in adirection transverse to the running direction of the felt, with said atleast one second guide roll in raised position, spreading said new feltto fit around all said respective rolls, and sliding said carriage meansin the direction transverse to the running direction of said felt. 3.The method of claim 1 in which said press section of said paper machinecomprises a plurality of nips, a first nip formed between said lowerpress roll and a suction roll, and a second nip formed between saidsuction roll and a smooth surfaced roll, and a second felt runningthrough said first and second nips.
 4. The method of claim 1 whichcomprises the additional step of removing said at least one second guideroll and lowering a new second guide roll in its place.